Benzoprostacycline derivatives of formula (I) are known in the U.S. Pat. No. 5,202,447 and Tetrahedron Lett. 31, 4493 (1990), and their general synthetic method is depicted in the following reaction scheme:

(Et: Ethyl, Ts: Tosyl, THF: Tetrahydrofuran, LAH: Lithium aluminum hydride, TBS: t-Butyldimethylsilyl, DMF: Dimethylformamide, pyr.: Pyridine, Ac: Acetyl, Me: Methyl)
Specifically, the above method comprises the steps of: i) forming a diol compound from a benzofuran ring via Prins reaction; ii) introducing a substituent to the benzene ring via Grignard reaction; iii) selectively protecting the diol, and then, introducing an ω-chain thereto via Wittig reaction; and iv) performing reduction, deacetylation and ester hydrolysis to the obtained compound under Luche condition. However, the method has drawbacks in that the diastereomeric mixture formed from reduction of C15 ketone after ω-chain introduction has extremely low stereo-selectivity, i.e. the isomers ratio of 45:55, and a very low yield, i.e. 40%, of the desired isomer.